Raphael's use of perspective

"Like many artists of the 1500's, Raphael was fascinated by formal composition. He used perspective to create a 3-D space in a flat painting. That may sound like old hat to us, but perspective was the hot new thing in those days.

Raphael's use of perspective. See how the whole painting is arranged around a vanishing point on the horizon? Everything follows the perspective lines to that point. And objects get smaller and higher in the painting, so they look like they're farther away."

I took it from this site which is very good for those who want to start to understand some aspects of painting.
Raphael, Titian, Millet, Van Gogh, Gauguin and Picasso are the artists whose paintings are used to explain very easily historical changes and personal choices of each of them.